In recent years, a regulation of exhaust emission becomes further strict, and reduction in fuel consumption of an engine is further required. In general, it is necessary to accurately control a shape of spray of fuel injected from a fuel injection valve and an injection amount of fuel, in order to conform to the regulation of exhaust emission and requirement of reduction in fuel consumption of an engine. Therefore, a fuel injection valve needs to be adjusted respectively to each engine and each vehicle in order to satisfy various kinds of injection characteristics, which are different for each engine and vehicle. According to JP-A-2005-180199, a nozzle plate having a nozzle holes is provided to a tip end of a fuel injection valve to facilitate adjustment of the injection characteristics of the fuel injection valve. In this structure, the injection characteristic of the fuel injection valve can be modified by changing the nozzle plate, without changing the basic structure of the fuel injection valve.
However, the nozzle plate has small nozzle holes. Accordingly, injected fuel is apt to remain around the nozzle holes. This remaining fuel may be solidified by being exposed to high temperature combustion gas, or subsequent to elapsing time after engine stop. This solidified fuel may accumulate as deposit around the jet nozzle. When deposit is accumulated around the nozzle holes, a spray direction, in which fuel is sprayed through the nozzle hole, and a shape of fuel spray may change. As a result, the performance of the injection valve may not be maintained.
According to JP-A-2002-206469, the outer circumferential periphery of the nozzle hole has a recession. In the structure disclosed in JP-A-09-236062, the segment around the nozzle hole protrudes along the spray direction, and the outer circumferential periphery of the nozzle hole is backwardly recessed, so that the space is formed around the nozzle hole. In this structure, fuel supplied through the nozzle hole is introduced into this space, so that the fuel is restricted from being deposited around the nozzle hole.
According to JP-A-2004-27857, the volume of the recession, in which the nozzle hole is formed, is reduced, so that the amount of fuel accumulating in the recession is reduced. Thus, the amount of deposit of fuel accumulating around the nozzle hole is reduced. In the structure disclosed in JP-A-2003-262170, the heat plate covers around the nozzle hole, so that the segment around the nozzle hole is restricted from being exposed to flame in the combustion chamber. In addition, the gap circumferentially formed between the heat plate and the nozzle hole is utilized as a thermally insulating body, so that fuel around the nozzle hole is restricted from becoming deposit due to increase in temperature around the nozzle hole.
According to JP-A-2002-48034, fuel around the nozzle hole is introduced to the radially outer side along the drain groove, thereby being restricted from becoming deposit.
However, in the structure disclosed in JP-A-2002-206469 and JP-A-09-236062, the space introducing fuel around the nozzle hole is formed on the surface on the radially outer side of the nozzle hole. Accordingly ,the space does not have a structure for sufficiently draining fuel from the nozzle hole.
In the structure disclosed in JP-A-2004-27857, fuel accumulating around the recession, in which the nozzle hole is formed, is reduced. In this structure, fuel is not necessarily removed from the nozzle hole.
In the structure disclosed in JP-A-2003-262170, the gap is circumferentially formed entirely between the heat plate and the surface around of the nozzle hole. In this structure, fuel introduced from the nozzle hole into the gap makes contact with only the surface around the nozzle hole and the surface of the heat plate. In this structure, fuel cannot be guided sufficiently into the gap. Accordingly, fuel cannot be removed from the nozzle hole.
In the above four patent documents, fuel may remain around the nozzle hole, consequently, remaining fuel may gradually accumulate to be deposit.
In the disclosure of JP-A-2002-48034, fuel around the nozzle hole is guided to the radially outer side along the drain groove utilizing gravitational force. Accordingly, the tilt angle of the fuel injection valve and the screwed angle of the fuel injection valve define the arrangement of the draining groove. In this structure, the tilt angle of the fuel injection valve and the screwed angle of the fuel injection valve need to be adjusted, consequently, an assembling work of the fuel injection valve becomes complicated.